This invention relates to diamond/metal composites particularly useful as electrical component mounting plates and enclosures.
Hermetically sealed enclosures for electrical components are desirable to protect the electrical components from damaging environmental conditions such as moisture and airborne dust. Electrical components and electrical circuits mounted in hermetically sealed enclosures are often used in equipment which is subjected to wide temperature and pressure variations. For instance, when electrical components are used on an aircraft which rises from ground level into the upper atmosphere the temperature can drop more than a hundred degrees fahrenheit. In addition, the electrical components often generate substantial amounts of heat which can be damaging to the components and/or their predictable operation.
Diamond/metal composites are well known as is the fact that the coefficient of thermal expansion ("CTE") of such composite is variable as a function of the diamond/metal ratio but not as to the particle size. It has been generally recognized that particles of small size are required to obtain a CTE compatible with the known uses of such composites.
By way of example, the composites disclosed in the Supan, et al. U.S. Pat. No. 5,045,972 contain 5 to 80 volume percent diamond particles with a particle size from 1 to 50 microns. Similarly, the composites disclosed in the Burnham, et al. U.S. Pat. No. 5,008,737 contain a diamond/metal ratio disclosed only as being compatible in its CTE with the CTE of a semiconductor material with which used with a particle size of its largest dimension no greater than 106 microns, preferably less than 38 microns and more preferably less than 3 microns.
In contrast, thermal conductivity is directly variable with particle size and applicants have discovered that, in direct contrast to the teachings of the known prior art to use diamond particles of extremely small size, diamond/metal composites may be made with large diamond particles thus enhancing the thermal conductivity of the material without affecting the CTE of the composite.
It is accordingly an object of the present invention to obviate many of the problems of the prior art and to provide a novel diamond/metal composite and method, which composite has particular utility in circuit card assembly thermal cores, multichip module substrate carriers, containers for electronic components and tamper proof electronic packaging.
It is another object of the present invention to provide a novel diamond/metal composite matched in CTE with the material with which used with enhanced thermal conductivity.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of preferred embodiments.